Method of preparing arylacetic acid alkyl esters

ABSTRACT

In a process of producing an alkyl ester of a substituted or unsubstituted arylacetic acid wherein a substituted or unsubstituted aromatic halogen methyl compound is reacted with carbon monoxide and an alcohol having an alkoxy group the same as that of said ester, the improvement which comprises carrying out said reaction in a basic reaction medium in the presence as catalyst of:

THE BACKGROUND

The present invention relates to a method of preparing arylacetic acidalkyl esters.

Several processes are known for the preparation of phenylacetic acidesters. Thus, phenylacetic acid esters may be obtained through thereaction of benzyl chloride with alkali cyanide followed bysaponification of the nitrile to the acid, and subsequent esterification(Ullmann, 1953, Vol. 4,291). What is unsatisfactory in this process isthe plurality of steps in the reaction. Phenylacetic acid esters mayalso be obtained through the carbonylization of benzyl halides with thesodium salt of cobalt octacarbonyl (R. F. Heck et al., J. Amer. Chem.Soc. 85, (1963) 2779-82, and French Pat. No. 1,313,306 of 1962). The useof the sodium cobalt carbonyl is extremely difficult technically andalso provides poor yields. Phenylacetic acid esters are also accessiblevia the carbonylization of benzyl halides with CO under pressure in thepresence of rhodium complexes (K. Ohno et al., J. Amer. Chem. Soc. 90,(1968) 99-107). Again, poor yields are obtained by this process, whichhas to be performed at higher pressures (100 atm.).

According to a new method of preparing phenylacetic acid esters, benzylchloride is brought to reaction in polar solvents such as dimethylformamide or dimethyl sulfoxide with carbon monoxide and alcohol in thepresence of nickel tetracarbonyl and iodine as catalyst and in thepresence of alkaline earth oxides as HCl acceptors (German"Offenlegungsschrift" No. 1,914,391). The disadvantages of this processresult from the large amounts of nickel carbonyl and iodine that areneeded as catalysts, and from the recovery of the expensive solventsused. On the basis of the long reaction time of 26.5 hours poorunit-volume yields are obtained, which make the process uneconomical.

THE INVENTION

It has now been found that, through the catalytic reaction of anaromatic methyl chloride compound with carbon monoxide in the presenceof a basic medium and the corresponding alcohols, the arylacetic acidester can be obtained directly.

Surprisingly, under the reaction conditions applied, the benzyl alkylether is not formed, as might be expected, from benzyl chloride andsodium alcoholate, for example, and instead the reaction takes place inaccordance with the following equation: ##STR1##

In this equation, R represents a saturated aliphatic alkyl radical with1 to 6 carbon atoms.

By arylacetic acid alkyl esters are meant the unsubstituted phenylaceticacid alkyl esters as well as substituted phenylacetic acid alkyl esters,condensed aromatic rings being able to be present as aryl radicals andbeing able to bear one or more additional substituents, preferablychlorine, alkyl radicals with 1 to 6 carbon atoms or alkoxy radicalswith 1 to 6 carbon atoms. Examples are mono-,di- andtetrachlorophenylacetic acid alkyl esters, monomethyl and dimethyl ormonopropyl and dipropyl phenylacetic acid alkyl esters, mono- anddi-methoxy or -ethoxyphenylacetic acid alkyl esters, naphthyl aceticacid methyl or ethyl esters, etc.

The starting materials are the structurally corresponding, unsubstitutedaromatic halogen methyl compounds or those bearing the desiredsubstituents, preferably the chloromethyl compounds.

The alcohols used and the alkyl radicals of the alkali alcoholates arethose corresponding structurally to the radicals entering into theparticular alkylester radicals of the phenylacetic acid alkyl esters,not only the primary but also secondary and tertiary alcohols or thecorresponding alcoholates being able to be used.

The carbon monoxide pressure may be 0.1 to 25 atmospheres, preferably0.1 to 10 atmospheres excess pressure.

The catalyst (a) may be a catalyst system consisting of threecomponents, namely a cobalt salt such as cobalt halide, cobalt acetate,cobalt-II-acetylacetonate, cobalt nitrate andcobalt-II-hydroxide-carbonate; metallic manganese, iron, nickel oralloys thereof such as iron-manganese alloys in finely divided form, awater-soluble sulfur compound such as sodium dithionite, sulfoxylates(Rongalite) or sodium sulfide-sodium thiosulfate.

The reaction takes place at atmospheric or slightly higher pressure andleads to the desired arylacetic ester with a high yield.

For the preparation of the catalyst system, CO or a CO-containing gasmixture such as water gas is introduced into a solution of CoCl.sub. 26H₂ O in alcohol, metal powder and Na₂ S₂ O₄ until no more appreciableamounts of CO are absorbed. The introduction of the CO takes place at10° to 100°, preferably 20 to 40°C, and continues for about 30 minutes.Then, at a temperature between 30° and 80°, preferably 50° to 60°C,while the introduction of CO is continued and intensified, the aromaticchloromethyl compound and the alkali alcoholates or alkaline earthoxides preferred as the alkaline medium are added in such quantity ratiothat the reaction medium always has an alkaline, preferably a weaklyalkaline, reaction. It is desirable that the sodium alcoholate be addedin the form of a 10 to 25 wt-% solution in alcohol. The aromaticchloromethyl compound may be added all at once to the catalyst mixtureor it may be fed in continuously. The feeding of CO and alcoholate tothe solution of the particular alcohol, or CaO with the particularalcohol, takes place for a period of about 3 to 5 hours. Theintroduction of CO is further continued until its absorption hasstopped. As a rule this absorption will end about 3 hours after theaddition of the components. As a rule, then, the total reaction time(including the preparation of the catalyst) will be 6 to 8 hours.

The molar ratio of basic reagent to aromatic methyl chloride compound ispreferably around 1:1, although slight excesses of the basic substancemay be used so that a weakly alkaline reaction will be maintained by aslight excess of the basic substance and an acid reaction will beavoided. A slow, constant or portion-wise addition of the basicsubstance during the reaction of the halogen methyl compound istherefore preferred.

The metal powder or alloy may be used in a particle size between 0.10and 300 microns, preferably between 50 and 200 microns. The ratio byweight of the metal powder or alloy to the chloromethyl compound canbest range between 1:1 and 1:1000, the upper limit being determined onlyby the ability of the reaction medium to be stirred. Preferably theratio will be between 1:10 and 1:100.

The process of the invention permits both the isolation and the recoveryof the metal powder or alloy. The weight ratio of the cobalt compound tothe methyl chloride compound may range between 1:1 and 1:500, preferably1:2 to 1:50. The sulfur compound is used in a small quantity, the weightratio of the sulfur compound to the methyl chloride compound beingbetween 1:3 and 1:1500, preferably between 1:30 and 1:500.

A metal carbonyl compound may be used as catalyst (b), the cobalt and/oriron carbonyls being preferred.

The reaction takes place at atmospheric or slightly higher pressure andresults in very high yields of the desired arylacetic ester, For thepreparation of the said ester, iron carbonyl or cobalt carbonyl isplaced in a saturated alcohol with 1 to 6 carbon atoms as the solventand CO or a CO-containing gas mixture such as water gas is introduced.Then, at a temperature between 10° and 100°C, preferably 50° to 60°C,with the continued introduction of CO, the substituted or unsubstitutedaromatic chloromethyl compound that is to be carbonylized, and a sodiumalcoholate of a saturated aliphatic, primary, secondary or tertiaryalcohol of 1 to 6 carbon atoms are added in such a quantity ratio thatthe reaction medium will always have an alkaline, preferably weaklyalkaline, reaction. The substituted or unsubstituted aromatic methylchloride to be carbonylized, however, may also be added all at once atthe beginning of the reaction. It is desirable that sodium alcoholate beadded in the form of a 10 to 30 wt-% solution in alcohol.

The catalyst may likewise be added all at once to the reaction solutionor it may be fed into it continuously. The introduction of carbonmonoxide is continued until absorption ceases. As a rule such absorptionwill have ceased about 3 to 8 hours after the addition of thecomponents.

The quantity ratio of basic reagent to the aromatic methyl chloridecompound is preferably 1:1, although slight excesses of the basicsubstance may be used so that a weakly alkaline reaction will bemaintained by a slight excess of the basic substance and an acidreaction will be avoided.

The weight ratio of metal carbonyl to the methyl chloride compound maybe between 1:1 and 1:500, preferably 1:20 to 1:200.

The processing of the reaction batch is particularly simple inasmuch asthe solid components (sodium chloride, metal powder) are simplyseparated by filtration. Water may be added to the filtrate, whereuponthe reaction product separates in fairly pure form as an organic phase.The aqueous phase consists of a mixture of alcohol and water whichcontains dissolved therein the cobalt compound and the sulfur compoundand the sodium salt of the arylacetic acid formed as by-product.

The filtrate may also be distilled directly, leaving small amounts ofsodium chloride and of the metal carbonyls used.

The phenylacetic esters preparated by the process of the invention finduse as perfumes and are valuable chemical intermediates.

EXAMPLE 1

To 100 ml of methanol were added 12 g of CoCl₂ . 6 H₂ O, 6 g of powderedmanganese (150 u) and 1 g of sodium dithionite, in a carbon monoxideatmosphere. Carbon monoxide was then passed through the mixture withstirring (500 rpm), for 30 minutes at 35°C, with an overpressure of 600mm Hg. Then the mixture was heated to 55°C and, over a period of 3hours, 190 g (1.5 moles) of benzyl chloride and 404 g (1.5 moles) of 21wt-% sodium methylate solution were added while constantly feeding incarbon monoxide and at a stirring speed of 500 to 750 rpm.

Carbon monoxide continued to be introduced for about 21/2 more hours,until no more absorption took place. Then the sodium chloride andmanganese were separated, water was added to the filtrate, and thefiltrate was extracted with ether. After distillation of the ether, areaction mixture remained from which 170 g of phenylacetic acid methylester (yield 78%, purity 99.7%) and 6.9 g of benzyl chloride wereisolated by distillation.

After acidification of the aqueous phase and extraction with ether, anadditional 18 g of phenylacetic acid was isolated (yield 9.1%, purity99.3%).

EXAMPLE 2

In the manner described in Example 1, 300 g of benzyl chloride, 620 mlof 21 wt-% sodium methylate and, as catalysts, 20 g of CoCl₂ .sup.. 6 H₂O, 1 g Na₂ S, 1.5 g Na₂ S₂ O₃.sup.. 5 H₂ O, and 9 g of powderedmanganese, were reacted with carbon monoxide. After the describedprocessing, the reaction mixture yielded 21 g benzyl chloride (93%transformation), 214 g of phenylacetic acid methyl ester (yield 64.7%)and 26 g of phenylacetic acid (yield 8.6%).

EXAMPLE 3

As described in Example 1, 190 g of benzyl chloride, 404 g of 21 wt-%sodium methylate and, as catalysts, 12 g CoBr₂.6 H₂ O, 6 g manganesepowder and 1 g Na₂ S₂ O₄, were reacted with carbon monoxide. 7 g ofbenzyl chloride, 125 g of phenylacetic acid methyl ester (yield 57.6%),13.4 g of phenylacetic acide (yield 6.8%) and 23 g of methylbenzyl etherwere isolated from the reaction mixture after the described processing.

EXAMPLE 4

As described in Example 1, 190 g of benzyl chloride, 404 g of 21 wt-%sodium methylate, 12 g of Co(CH₃ COO)₂.sup.. 4 H₂ 0, 6 g of powderedmanganese and 1 g of Na₂ S₂ O₄ were reacted with CO. 2.9 g of benzylchloride, 152 g of phenylacetic acid methyl ester (yield 68.5%), 5 g ofphenylacetic acid (yield 2.5%) and 11 g of methylbenzyl ether (yield 6%)were isolated from the reaction mixture after the described processing.

EXAMPLE 5

As described in Example 1, 190 g of benzyl chloride, 100 g of calciumoxide, 750 ml of methanol, 6 g CoCl₂.sup.. 6 H₂ O, 6 g manganese powderand 3 g Na₂ S₂ O₄ were reacted with Co, the calcium oxide being addedover a period of 3 hours. 10 g of benzyl chloride, 122 g phenylaceticacid methyl ester (yield 57%), 37 g phenylacetic acid (yield 19%) and 2g methylbenzyl ether were isolated from the reaction mixture after thedescribed processing.

EXAMPLE 6

As described in Example 1, 126.5 g of benzyl chloride, 270 g of 21 wt-%sodium methylate, 11 g Co₂ (CO)₈, 4 g manganese and 1 g Na₂ S₂ O₄ werereacted with CO. 133.5 g of phenylacetic acid methyl ester (yield 89%)was isolated from the reaction mixture in a purity of 97.25%.

EXAMPLES 7 to 16

In the examples listed in the following table, 190 g of benzyl chloride(1.5 moles) were reacted in each case with CO in the presence of thespecified catalysts. The basic agent in each case was 355 g of a 24 wt-%solution of sodium methylate in methanol.

                                      TABLE I                                     __________________________________________________________________________    Catalyst System                                                               Example                        Dist.                                          No.  Metal  Cobalt compound                                                                         Sulfur compound                                                                        in g                                           __________________________________________________________________________    7    4 g Mn 6 g CoCl.sub.2.6H.sub.2 O                                                               Rongalite 1 g                                                                          185                                            8    6 g Ni 12 g CoCl.sub.2.6H.sub.2 O                                                              Na.sub.2 S.sub.2 O.sub.4 1 g                                                           165                                            9    6 g Fe 12 g CoCl.sub.2.6H.sub.2 O                                                              "        160                                            10   4 g Mn.sup.+.sup.)                                                                   6 g CoCl.sub.2.6H.sub.2 O                                                               "        200                                                 45 -                                                                          150 μ                                                                 11   6 g Mn 12 g CoII-                                                                              "        192                                                        acetylacetonate                                                               CoI                                                               12   6 g Mn 12 g CoJ.sub.2.2H.sub.2 O                                                               "        200                                            13   6 g Mn.sup.+.sup.)                                                                   12 g CoCl.sub.2.6H.sub.2 O                                                              "        184                                                 0.15 mm                                                                  14   6 g Mn.sup.+.sup.+.sup.)                                                             12 g CoCl.sub.2.6H.sub.2 O                                                              "        180                                                 0.15 mm                                                                  15   6 g Mn 12 g Co(NO.sub.3).sub.2.                                                                "        163,5                                                      6H.sub.2 O                                                        16   6 g Fe/Mn                                                                            12 g CoCl.sub.2.6H.sub.2 O                                                              "        160                                            __________________________________________________________________________     .sup.+.sup.) = Thermally produced                                             .sup.+.sup.+.sup.) = Electrolytically produced                           

                                      TABLE II                                    __________________________________________________________________________    Gas chromatogr. analysis of the distillate.sup.+.sup.+.sup.+                  Example                                                                       No.  PhCH.sub.2 Cl                                                                      PhCH.sub.2 OCH.sub.3                                                                 PhCH.sub.2 COOCH.sub.3                                                                PhCH.sub.2 COOH                                                                      PhCH.sub.2 COOCH.sub.2 Ph                     __________________________________________________________________________    7    3.89 18.94  72.17   3.63   0.43                                          8    24.11                                                                              58.59  12.62   4.28   --                                            9    21.18                                                                              63.68  9.21    5.43   --                                            10   2.97 11.90  79.87   0.28   0.28                                          11   2.72 38.33  57.43   0.18   0.44                                          12   0.34 5.17   92.41   1.04   0.84                                          13   11.19                                                                              35.41  43.99   7.75   0.51                                          14   17.08                                                                              41.96  30.03   9.13   0.48                                          15   12.28                                                                              17.97  61.58   6.51   0.53                                          16   9.51 10.87  69.65   8.23   0.64                                          __________________________________________________________________________     .sup.+.sup.+.sup.+in wt-% with reference to the                               The chromatography column had a packing of Silicone Gum Rubber UCC W-982      (methyl vinyl)                                                           

EXAMPLE 17 Phenylacetic acid methyl ester:

2.5 g CoCl₂.sup.. 6 H₂ O, 2 g manganese powder (150 u) and 1 g Na₂ S₂ O₄were added to 100 ml of methanol in a CO atmosphere. Then CO was passedthrough the mixture with stirring (500 rpm) at 35°C for 30 minutes withan overpressure of 600 mm Hg. At 55°C, 190 g of benzyl chloride wasadded to the reaction mixture. Then, over a period of 3 hours with thesteady passage of CO, 355 g of 24 wt-% sodium methylate solution was fedin with a stirring speed of 500 to 750 rpm. Carbon monoxide wasintroduced for another 21/2 hours, approximately, until no moreabsorption took place. Then water was added to the mixture and thelatter was separated from the manganese. The mixture was extracted withether. After the ether was removed by distillation there remained areaction mixture from which 3.5 g of benzyl chloride and 189 g ofphenylacetic acid methyl ester (yield 85.4%) were isolated bydistillation.

After acidification of the aqueous phase and extraction with ether, itwas possible to isolate an additional 5 grams of phenylacetic acid(yield 2.5%).

EXAMPLE 18 p-Chlorophenylacetic acid methyl ester:

As described in Example 1, 80.5 g (0.5 mole) of p-chlorobenzyl chloridewith 135 g of a 24 wt-% sodium methylate solution, 10 g of CoCl₂.sup.. 6H₂ O, 4 g of manganese and 1 g of sodium dithionite were reacted withCO. The reaction and processing were performed as described inExample 1. 74 g of p-chlorophenylacetic acid methyl ester (yield 80%)was isolated in a purity of 96%, plus 4 g of p-chlorophenylacetic acid(4.6%).

EXAMPLE 19 p-Methylphenylacetic acid methyl ester

In the manner described in Example 1, 70.5 g (0.5 mole) ofp-methylbenzyl chloride and 135 g of a 24 wt-% sodium methylate solutionin methanol, 5 g CoCl₂.sup.. 6 H₂ O, 4 g manganese powder and 1 g sodiumdithionite were reacted with CO. The reaction and the processing wereperformed as described in Example 1. 47.0 g of p-methylphenylacetic acidmethyl ester (BP₁₃ 113°) (yield 57.2%) was isolated in a purity of 98%,plus 6.2 of p-methylphenylacetic acid (MP 89°-90°C, yield 8%).

EXAMPLE 20 Naphthyl-(1)-acetic acid methyl ester

In the manner described in Example 1, 58 g ofalphachloromethylnaphthalene was reacted with CO together with 78 g of a24 wt-% sodium methylate solution in methanol, 12 g CoCl₂.sup.. 6 H₂ O,6 g manganese and 1 g Na₂ S₂ O₄. The usual processing yielded 35 g ofnaphthyl-(1)-acetic acid methyl ester (yield 53%) and 7 g ofalpha-naphthylacetic acid (yield 6.5%).

EXAMPLE 21 p-Methoxyphenylacetic acid methyl ester:

In the manner described in Example 1, 50 g of p-methoxybenzyl chloridewas reacted with CO together with 115 g of a 24 wt-% solution of sodiummethylate in methanol, 12 g CoCl₂.sup.. 6 H₂ O , 6 g manganese and 1 gNa₂ S₂ O₄. After distillation of the reaction mixture the followingcompounds could be identified by gas chromatography:p-methoxybenzylchloride 10.00%p-methoxymethylbenzylether69.50%-p-methoxyphenylaceticacid methyl ester8.66%p-methoxyphenylaceticacid 5.54%

EXAMPLE 22 Phenylacetic acid ethyl ester:

In a manner similar to Example 17, 126.5 g of benzyl chloride, 794 g ofa 9 wt-% solution of sodium ethylate in ethanol, 12 g CoCl₂.sup.. 6 H₂O, 6 g manganese powder and 1 g Na₂ S₂ O₄ were reacted with CO. Afterthe usual processing, 8 g of benzyl chloride, 109 g of phenylacetic acidethyl ester (yield 71%), 8 g of phenylacetic acid (yield 6%) and 1 g ofethylbenzyl ether were isolated.

EXAMPLE 23

In a manner similar to Example 1, 63.5 g (1/2 mole) of benzyl chloride,6 g CoCl₂.sup.. 6 H₂ O, 4 g manganese powder, 1 g Na₂ S₂ O₄ in 100 ml oftert. butanol and 56 g of potassium tertiary butylate were reacted withCO. The reaction and processing were performed as in Example 1.

55 g of reaction mixture was distilled, which on the basis of gaschromatography contained the following:

    Benzyl chloride  18.6%                                                        Phenylacetic acid                                                             tert. butyl ester                                                                              79.18%                                                   

EXAMPLE 24

In the manner described in Example 17, 190 g of benzyl chloride, 329 gof 25.8 wt-% sodium methylate, 12 g of CoCl₂.sup.. 6 H₂ O, 6 g manganesepowder and 1 g Na₂ S₂ O₄ were reacted with a mixture of carbon monoxideand hydrogen gas in a ratio of 3:1.

After distillation of the reaction mixture (180 g) the following resultswere obtained by gas chromatography:

    Benzyl chloride  20.24%                                                       Methylbenzyl ether                                                                             25.43%                                                       Phenylacetic acid                                                             methyl ester     44.76%                                                       Phenylacetic acid                                                                               5.31%                                                   

EXAMPLE 25

In the manner described in Example 1, 190 g of benzyl chloride togetherwith 355 g of 24 wt-% NaOCH₃, 12 g of cobalt (II)-hydroxidecarbonate*.sup.) 6 g of manganese and 1 g of Na₂ S₂ O₄ were reacted withCO. 175.5 g was distilled which, according to GC, contained thefollowing:

    Benzyl chloride  10.43%                                                       Methylbenzyl ether                                                                             82.77%                                                       Phenylacetic acid                                                             methyl ester      6.1%                                                    

EXAMPLE 26

6 g of cobalt octacarbonyl was added to 100 ml of methanol. Then CO waspassed through with stirring (500 rpm) at 35°C for 30 minutes with anexcess pressure of 600 mm Hg. Then the mixture was heated to 55°C and,with a steady feed-through of CO, 190 g (1.5 mole) of benzyl chlorideand 329 g of 25.8 wt-% sodium methylate were fed in over a period of 3hours at a stirring speed of 500 to 750 rpm. Carbon monoxide deliverycontinued for about 21/2 more hours until no further absorption tookplace. Then water was mixed with the reaction mixture and it wasextracted with ether. After distilling the ether a reaction mixture wsobtained from which 215 g of phenylacetic acid methyl ester in a purityof 97.03% was obtained by distillation (yield 95.4%).

EXAMPLE 27

In the manner described in Example 26, 4 g of Co₂ (CO)₈, dissolved in100 ml of ethanol, 126.5 g of benzyl chloride and 794 g of 9 wt-% ofNaOC₂ H₅ dissolved in ethanol (H₂ O content 0.17%) were reacted with CO.The reaction and the processing were performed as in Example 26. 136 gof reaction mixture was distilled, which according togas-chromatographic analysis (GC) had the following composition:

2.37% ethylbenzyl ether

2.53% benzyl chloride

70.75% phenylacetic acid ethyl ester

13.79% phenylacetic acid

EXAMPLE 28

In the manner described in Example 26, 3 g of Co₂ (CO)₈, 80.5 g (0.5mole) of p-chlorobenzyl chloride and 110 g of 25.8 wt-% sodium methylatewere reacted with CO. The reaction and processing were performed as inExample 26. 6.5 g of p-chlorobenzylchloride and 76 g of pchlorophenylacetic acid methyl ester (yield 89.8%) were distilled in apurity of 97.75%.

EXAMPLE 29

In the manner described in Example 26, 4 g of Co₂ (CO)₈, 70.5 g (0.5mole) of p-methylbenzyl chloride and 110 g of 25.8 wt-% sodium methylatewere reacted with CO. The reaction and the processing were performed asin Example 26. 2 grams of p-methylbenzyl chloride and 69 g ofp-methylphenyylacetic acid methyl ester (yield 86.7%) were distilled ina purity of 99.25%.

EXAMPLE 30

In the manner described in Example 26, 4 g of Co₂ (CO)₈, 76 g (0.43mole) of α-chloromethylnaphthalene and 95 g of sodium ethylate werereacted with CO. The reaction and processing were performed as inExample 26.

After the distillation of the reaction mixture (65 g), the followingwere determined by GC:

39.2% methoxymethylnaphthaline

3.03% chloromethylnaphthaline

54.27% naphthyl-(1)-acetic acid methyl ester.

EXAMPLE 31

In the manner described in Example 26, 4 g of Co₂ (CO)₈, 57 g (0.36mole) of p-methoxybenzyl chloride and 78 g of 25.8 wt-% sodium methylatewere reacted with CO. After processing, 50 g were distilled. Thefollowing compounds were determined by GC:

30.8% p-methoxymethylbenzyl ether

24.76% p-methoxybenzyl chloride

40.93% p-methoxyphenylacetic acid methyl ester.

EXAMPLE 32

In the manner described in Example 26, 9 ml of Fe(CO)₅, 190 g of benzylchloride and 329 g of 25.8 wt-% sodium methylate were reacted with CO.The reaction and processing were performed as in Example 26. Afterdistillation of the reaction mixture the following compounds weredetermined by GC:

6.03% benzyl chloride

55.76% methyl benzyl ether

34.07% phenylacetic acid methyl ester.

EXAMPLE 33

In the manner described in Example 26, 22 ml of Fe(CO)₅, 190 g of benzylchloride and 329 g of 25.8 wt-% sodium methylate were reacted with CO.175 grams of distillate were obtained with the following compositionaccording to GC:

0.81% benzyl chloride

4.56% methylbenzyl ether

90.61% phenylacetic acid methyl ester

EXAMPLE 34

In the manner described in Example 26, 6 g of Co₂ (CO)₈, 190 g of benzylchloride and 329 g of 25.8 wt-% sodium methylate were reacted with aCO/H₂ gas mixture in a 3:2 ratio. 173 g were distilled with thefollowing composition:

4.92% benzyl chloride

63.52% methylbenzyl ether

25.91% phenylacetic acid methyl ester

EXAMPLE 35

In the manner described in Example 26, 4 g of Co₂ (CO)₈, 100 ml ofmethanol, 126.6 g (1 mole) of benzyl chloride and 56 g of CaO werereacted with CO. The reaction was performed as in Example 26. After thatthe mixture was acidified with hydrochloric acid and processed as inExample 26.

104 g of reaction mixture was distilled, which contained the followingcomposition according to GC:

    Benzyl chloride  32.83%                                                       Phenylacetic acid                                                             methyl ester     40.71%                                                       Phenylacetic acid                                                                              22.88%                                                   

EXAMPLE 36

In the manner described in Example 26, 2.5 g of Co₂ (CO)₈, 100 ml oftertiary butanol, 63.5 g (1/2 mole) of benzyl chloride and 56 g ofpotassium-tertiary-butylate were reacted with CO. The reaction andprocessing were performed as in Example 26.

52 g of reaction mixture were distilled, which contained the followingcomposition according to GC:

    Tertiary butanol 11.16%                                                       Benzyl chloride  12.45%                                                       Phenylacetic acid                                                             tert.-butyl ester                                                                              74.18%                                                   

EXAMPLE 37

By the procedure described in Example 26, 4 g of Co₂ (CO)₈, 55 g of4-isopropyl-1-chloromethylbenzene and 100 g of 25.8 wt-% sodiummethylate were reacted with CO. After processing 47 g ofp-isopropylphenylacetic acid methyl ester were isolated.

What is claimed is:
 1. In a process of producing an alkyl ester of asubstituted or unsubstituted arylacetic acid wherein a correspondinglysubstituted or unsubstituted benzyl halide is reacted with carbonmonoxide and an alcohol having an alkoxy group the same as that of saidester, the improvement which comprises carrying out said reaction in abasic reaction medium at a temperature of about 10°-100°C, and a carbonmonoxide pressure of about 0.1-25 atmospheres in the presence ascatalyst ofwhich is at least one of Co₂ (CO)₈ and Fe(CO)₅.
 2. Processaccording to claim 1, wherein carbon monoxide is added in admixture withanother gas.
 3. Process according to claim 1, the metal carbonylcompound being Co₂ (CO)₈.
 4. Process according to claim 1, the metalcarbonyl compound being Fe(CO)₅.
 5. Process according to claim 1,wherein the benzyl halide is benzyl chloride.
 6. Process according toclaim 1, wherein the benzylhalide is unsubstituted or substituted bychlorine, alkyl of 1-6 carbon atoms or alkoxy of 1 to 6 carbon atoms; orcondensed with another ring.